The Quit Using Drugs Intervention Trial (QUIT) will be the first randomized controlled trial in the U.S. that is powered to detect the effect of a primary care clinician delivered brief intervention protocol for reducing `at risk'drug use and drug-related harm among low-income adult patients (ages 18 and older) at 2 safety net clinics in Los Angeles County. For this small trial, we will sample patients with `at risk'use of stimulants (cocaine or amphetamines), the most commonly used serious drugs among patients at our clinic sites. "At risk" stimulant use is defined in this study as current use (past 90 days) of stimulants measured as a self-reported total score of 4 to 26 on the WHO Alcohol Substance Involvement Screening Test (ASSIST). A total of 8,000 patients will be approached for screening to yield a 12-month effective sample size of 200 eligible patients per condition (1) an intervention condition or (2) a control condition involving care as usual. In the intervention condition, very brief (less than 5 minutes) clinician advice regarding quitting stimulants use will be followed by two 2 and 6 week post-visit drug health education sessions on quitting stimulant use and cautioning against use of other `at risk'substance use such as alcohol and tobacco. Patients assigned to the control condition will receive standard care for drug use at the baseline visit with their clinician, which will be followed by two post-visit telephone health education sessions that will be of equal duration as the intervention sessions but will address healthy eating, physical activity, and seat belt use. Follow- up assessments will be conducted at 6 and 12 months post-randomization. The framework for the QUIT project is the Social Action Theory, and the brief intervention protocol is based on NIDA's principles on prevention research and the utility of the 5 A's approach for assisting behavioral changes among patients (Ask, Advise, Assess, Assist, Arrange) in the clinic setting. If found to be effective in the community health center setting, this clinician and telephone stimulant-use health education program could become a model for health promotion activities. that would be expanded to all `at risk'substance use and shared between community health centers. PUBLIC HEALTH RELEVANCE: The proposed study will address the critical need to reduce illegal drug use, in particular stimulant use, and the occurrence of drug-related harm in low-income racially diverse patient populations at urban primary care safety-net clinics. At risk for accelerated trajectories to drug dependence once drug use begins, low-income racially diverse populations pose particular concern for public health policy makers and drug-use prevention efforts. The study will be the first of its kind to standardize drug screening and physician brief intervention among racially diverse "at risk" stimulant users, that is casual or frequent use without the physiological or psychological manifestations of dependence, and it may effectively interrupt their pathway to dependence.